util: ParseByteUnits - Parse a string with suffix unit [k|K|m|M|g|G|t|T]

A convenience utility for human readable arguments/config e.g. -maxuploadtarget=500g

1 files changed, 46 insertions, 0 deletions

diff --git a/src/util/strencodings.cpp b/src/util/strencodings.cpp
index 15bd07b374..5e7c99f140 100644
--- a/src/util/strencodings.cpp
+++ b/src/util/strencodings.cpp
@@ -11,6 +11,7 @@
 #include <algorithm>
 #include <cstdlib>
 #include <cstring>
+#include <limits>
 #include <optional>
 
 static const std::string CHARS_ALPHA_NUM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
@@ -526,3 +527,48 @@ std::string HexStr(const Span<const uint8_t> s)
     assert(it == rv.end());
     return rv;
 }
+
+std::optional<uint64_t> ParseByteUnits(const std::string& str, ByteUnit default_multiplier)
+{
+    if (str.empty()) {
+        return std::nullopt;
+    }
+    auto multiplier = default_multiplier;
+    char unit = str.back();
+    switch (unit) {
+    case 'k':
+        multiplier = ByteUnit::k;
+        break;
+    case 'K':
+        multiplier = ByteUnit::K;
+        break;
+    case 'm':
+        multiplier = ByteUnit::m;
+        break;
+    case 'M':
+        multiplier = ByteUnit::M;
+        break;
+    case 'g':
+        multiplier = ByteUnit::g;
+        break;
+    case 'G':
+        multiplier = ByteUnit::G;
+        break;
+    case 't':
+        multiplier = ByteUnit::t;
+        break;
+    case 'T':
+        multiplier = ByteUnit::T;
+        break;
+    default:
+        unit = 0;
+        break;
+    }
+
+    uint64_t unit_amount = static_cast<uint64_t>(multiplier);
+    auto parsed_num = ToIntegral<uint64_t>(unit ? str.substr(0, str.size() - 1) : str);
+    if (!parsed_num || parsed_num > std::numeric_limits<uint64_t>::max() / unit_amount) { // check overflow
+        return std::nullopt;
+    }
+    return *parsed_num * unit_amount;
+}